This invention relates in general to systems and methods for controlling the operation of an electro-hydraulic actuator. In particular, this invention relates to a system and method in which an increasing, linear commanded valve position signal is held constant for a short period of time when the signal reaches a valve position corresponding to a threshold hydraulic fluid pressure at which the hydraulic actuator begins to move.
In general, an electro-hydraulic actuator includes a cylinder having a piston disposed therein which is connected for movement with a mechanical device. The piston and the controlled device are moved under the influence of pressurized hydraulic fluid supplied to the interior of the hydraulic cylinder in response to the opening and closing of solenoid valves. The electronic controller controls the operation of the valves so as to cause the movement of the controlled device from an existing position to a desired position.
In the past, the electronic controller operated the solenoid valves to apply an increasing linear pressure against the piston to cause movement of the controlled mechanical device. In actual practice, however, it has been found that the piston does not initially move until a predetermined amount of pressure is applied thereto. As a result, the piston has been found to initially remain stationary, then subsequently jerk into initial movement which continues until the desired position is reached. Thus, it would be desirable to provide a control system and method for an electro-hydraulic actuator which eliminates this undesirable initial jerking movement.